Integrated multi-mode mammography/tomosynthesis X-ray system and method

ABSTRACT

A system for multi-mode breast x-ray Imaging which comprises a compression arm assembly for compressing and immobilizing a breast for x-ray imaging, an x-ray tube assembly, and an x-ray image receptor is provided. The system is configured for a plurality of imaging protocols and modes.

RELATED APPLICATION

This application is a continuation application and claims priority under35 USC §120 to U.S. patent application Ser. No. 14/058,385, filed Oct.21, 2013; which is a continuation of U.S. patent application Ser. No.13/462,342, filed May 2, 2012; which is a continuation of U.S. Pat. No.8,175,219, filed Nov. 29, 2010; which is a continuation of U.S. Pat. No.7,869,563, filed February 2008; which is a national stage entry ofPCT/US2005/042613, filed Nov. 23, 2006; which claims priority to and thebenefit of U.S. provisional patent application No. 60/631,296, filedNov. 26, 2004. Each of the above is incorporated by reference.

FIELD OF THE INVENTION

This patent specification pertains to x-ray mammography and, morespecifically, to an integrated system for selectively carrying out x-raymammography and/or tomosynthesis imaging and a method of using such asystem.

BACKGROUND OF THE INVENTION

X-ray mammography has long been a screening modality for breast cancerand other lesions, and also has been relied on for diagnostic and otherpurposes. For many years, the breast image was recorded on x-ray filmbut more recently digital x-ray image receptors have come into use, asin the Selenia™ mammography system available from Hologic, Inc ofBedford, Mass. and its division Lorad Corporation of Danbury, Conn. Formammograms, a cone-shaped or pyramid-shaped x-ray beam passes throughthe compressed breast and forms a two-dimensional projection image. Anyone of a number of orientation can be used, such as cranial-caudal (CC)or MLO (mediolateral-oblique) orientation. More recently, breast x-raytomosynthesis has been proposed. The technology typically involvestaking two-dimensional (2D) projection images of the immobilized breastat each of a number of angles of the x-ray beam relative to the breastand processing the resulting x-ray measurements to reconstruct images ofbreast slices that typically are in planes transverse to the x-ray beamaxis, such as parallel to the image plane of a mammogram of the samebreast. The range of angles is substantially less than in computerizedtomography, i.e., substantially less than 180°, e.g. ±15°. Tomosynthesistechnology is described in U.S. patent application Ser. No. 10/723,486filed Nov. 26, 2003; a prototype of a unit with at least some of thedescribed features was shown at the 2003 Radiological Society of NorthAmerica meeting in Chicago, Ill. Additional prototypes are in clinicaltexting in this country as of the filing of this patent specification.Other approaches to tomosynthesis also have been proposed; e.g., U.S.Pat. Nos. 4,496,557, 5,051,904, 5,359,637, 6,289,235, and 6,647,092,published U.S. Patent Applications Nos. 2001/0038861, 2004/066882,2004/0066884, and 2004/0066904, and Digital Clinical Reports.Tomosynthesis (GE Brochure 98-5493, 11/98). How to reconstructtomosynthesis images is discussed in DG Grant, “Tomosynthesis: athree-dimensional imaging technique”, IEEE Trans. Biomed. Engineering,Vol BME-19, #1, (January 1972), pp 20-28. See, also, U.S. ProvisionalApplication Ser. No. 60/628,516, filed Nov. 15, 2004, and entitled“Matching geometry generation and display of mammograms andtomosynthesis images”. Mammography systems can also be used ininterventional procedures, such as biopsy, by adding a biopsy station(for example, the StereoLoc II™ Upright Stereotactic Breast BiopsySystem, which is available from Hologic, Inc.). The patents,applications, brochures, and article cited above are hereby incorporatedby reference in this patent specification as though fully set forthherein.

In clinical use, it can be desirable for a number of reasons to assessboth tomosynthesis images and conventional mammograms of the patient'sbreasts. For example, the decades of conventional mammograms haveenabled medical professionals to develop valuable interpretationexpertise. Mammograms may offer good visualization ofmicrocalcifications, and can offer higher spatial resolution comparedwith tomosynthesis. Tomosynthesis images may have different desirablecharacteristics—e.g., they may offer better visualization of structuresthat can be obscured by overlying or underlying tissue in a conventionalmammogram.

While the existing and proposed systems for x-ray mammography andtomosynthesis offer many advantages, it is believed that a need stillexists for further improvements to make mammography/tomosynthesis moreuseful, and that it is particularly desirable to make it possible to usethe same system in different modes of operation and thereby reduceacquisition and operating costs and provide greater clinical value andconvenience.

SUMMARY

This patent specification describes examples of systems and methods formulti-mode breast x-ray imaging. A single system carries out breastimaging in modes that include standard mammography, diagnosticmammography, dynamic imaging such as with a contrast agent and atdifferent x-ray energies, tomosynthesis imaging, combined standard andtomosynthesis imaging during a single breast compression, needlelocalization, and stereotactic imaging with a biopsy station mounted tothe system.

In an example of a system using the teachings of this patentspecification, a compression arm assembly for compressing andimmobilizing the breast for x-ray imaging, as x-ray tube assembly, andan x-ray image receptor can be angled relative to each other fordifferent imaging protocols and modes. They can be independently rotatedand synchronized as needed, or can be mechanically linked forappropriate synchronized rotation. A patient shield can be mounted tothe compression arm assembly to provide a mechanical interlock againstpatient contact with the rotating x-ray tubes assembly. A fullyretractable anti-scatter grid can be used that can cover the imagingarea of the x-ray receptor in some modes but be retracted completelyoutside the imaging area for other modes.

The exemplary system further includes a breast compression paddle thatis laterally movable, under manual control or when motorized andoperating under software control. The compression paddle can shiftautomatically depending on the view to be acquired. For example, thepaddle can be centered on the x-ray receptor for a CC view, shifted toone lateral side of the receptor for an MLO view of one breast and tothe other lateral side of the receptor for an MLO view of the otherbreast. The paddle can be automatically recognized by the system whenmounted so that the shifts can be adjusted to the type of paddle.

The compression paddle can be easily removable from a support that has amechanism for laterally moving the paddle and for allowing the paddle totilt for better conformance with the breast for selected image modes butlocking the paddle against tilt for other modes. With the movementmechanism in the support and not integral with the paddle, the paddlecan be simple and inexpensive, and easy to mount to and remove from thesupport. A number of relatively inexpensive paddles of different sizesand shaped can be provided and conveniently interchanged to suitdifferent procedures and patients.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a gantry and an acquisition workstationin accordance with an example of the disclosed system.

FIG. 2 is an enlarged view of a portion of the system of FIG. 1, with atube arm assembly in a rotated position.

FIG. 3 is a front elevation of the apparatus of FIG. 2.

FIG. 4 is a side view of a gantry with a biopsy station and a spacer,with schematic illustration of other mechanisms.

FIG. 5 is an enlarged view of a portion of FIG. 1.

FIG. 6 is a block diagram of the disclosed system when connected toother systems.

FIG. 7 is a flow chart illustrating a general work flow for thedisclosed system.

FIG. 8 is a flow chart illustrating one of several examples of work flowfor a standard mammography mode.

FIG. 9 is a flow chart illustrating one of several examples of work flowfor an image detector subsystem in the standard mammography mode.

FIG. 10 is a perspective view of the structure of FIG. 4.

FIG. 11 is similar to FIG. 2 but shows a tube arm assembly angleddifferently.

FIG. 12 is a front elevation of the structure of FIG. 11.

FIG. 13 is a flow chart illustrating one of several examples of workflow for a tomosynthesis mode.

FIG. 14 is a flow chart illustrating one of several examples of workflow for an image detector subsystem in the tomosynthesis mode.

FIG. 15 is a flow chart illustrating one of several examples of workflow for a combination mode.

FIG. 16 is a flow chart illustrating one of several examples of workflow for an image detector subsystem in the combination mode.

FIG. 17 is an enlarged side view of a structure for removably mounting abreast compression paddle.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In describing examples and preferred embodiments illustrated in thedrawings, specific terminology is employed for the sake of clarity.However, the disclosure of this patent specification is not intended tobe limited to the specific terminology so selected and it is to beunderstood that each specific element includes all technical equivalentsthat operate in a similar manner.

FIGS. 1-6 illustrate a non-limiting example of a multi-modemammography/tomosynthesis system comprising a gantry 100 and a dataacquisition work-station 102. Gantry 100 includes a housing 104supporting a tube arm assembly 106 rotatably mounted thereon to pivotabout a horizontal axis 402 (FIG. 4) and carrying an x-ray tube assembly108. X-ray tube assembly 108 includes (1) an x-ray tube generating x-rayenergy in a selected range, such as 20-50 kV, at mAs such as in therange 3-400 mAs, with focal spots such as a nominal size 0.3 mm largespot and nominal size 0.1 mm small spot (2) supports for multiplefilters such as molybdenum, rhodium, aluminum, copper, and tin filters,and (3) an adjustable collimation assembly selectively collimating thex-ray beam from the focal spot in a range such as from 7×8 cm to 24×29cm when measured at the image plane of an x-ray image receptor includedin the system, at a maximum source-image distance such as 75 cm. Alsomounted on housing 104, for rotation about the same axis 402, is acompression arm assembly 110 that comprises a compression plate 122 anda receptor housing 114 having an upper surface 116 serving as a breastplate and enclosing a detector subsystem system 117 comprising a flatpanel x-ray receptor 502 (FIG. 5), a retractable anti-scatter grid 504and a mechanism 506 for driving and retracting anti-scatter grid 504.Housing 104 also encloses the following components schematicallyillustrated in FIG. 4; a vertical assembly 404 for moving tube armassembly 106 and compression arm assembly 110 up and down to accommodatea particular patient or imaging position, a tube arm assembly rotationmechanism 406 to rotate tube arm assembly 106 about axis 402 fordifferent imaging positions, a detector subsystem rotation mechanism 408for rotating components of detector subsystem 117 (such as x-rayreceptor 502) about axis 402 to accommodate different operations modes,and couple/uncouple mechanism 410 to selectively couple or uncouple tubearm assembly 106 and compression arm assembly 110 to and from eachother, and tube arm assembly 106 and detector subsystem 117 to and fromeach other. Housing 104 also encloses suitable motors and electrical andmechanical components and connections to implement the functionsdiscussed here. A patient shield 200, schematically illustrated in FIG.2, can be secured to compression arm assembly 110 to provide amechanical interlock against patient contact with the rotating x-raytube arm assembly 106. Workstation 102 comprises components similar tothose in the Selenia™ mammography system, including a display screen(typically a flat panel display that may include touch-screenfunctionality), user interface devices such as a keyboard, possibly atouch-screen, and a mouse or trackball, and various switches andindicator lights and/or displays. Work-station 102 also includescomputer facilities similar to those of the Selenia™ system (but adaptedthrough hardware, firmware and software differences) for controllinggantry 100 and for processing, storing and displaying data received fromgantry 100, A power generation facility for x-ray tube assembly 108 maybe included in housing 104 or in work-station 102. A power source 118powers work-station 102. Gantry 100 and work-station 102 exchange dataand controls over a schematically illustrated connection 120.

As illustrated in FIG. 6, additional storage facilities 602 can beconnected to work-station 102, such as one or more optical disc drivesfor storing information such as images and/or for providing informationto work-station 102 such as previously obtained images and software, ora local printer (not shown). In addition, the disclosed system can beconnected to a hospital or local area or other network 604, and throughthe network to other systems such as a soft copy workstation 606, a CAD(Computer Aided Detection) station 608 for computer-processingmammography and/or tomosynthesis images to identify likelyabnormalities, an image printer 610 for printing images, a technologistworkstation 612, other imaging systems 614 such as other mammographysystems or systems for other modalities for exchange of images and/orother information, and to a PACS (Picture Archiving) systems 616 forarchiving images and other information and/or retrieving images andother information.

The illustrated system has several modes of operation. An example of atypical workflow generally applicable for each mode is illustrated inFIG. 7, and several examples of operational modes are discussed below.Of course, this is only one example and workflow steps may be arrangeddifferently. In all modes, the operator can perform x-ray exposure usingmanual setting of technic factors such as mA and mSec, or can use anautomatic exposure control as known in the art to set the exposure time,kV and filter modes for an image, for example by using a short,low-x-ray dose pre-exposure. Work-station 102 is set up to record theexposure technic information and associate it with the breast image forlater review.

In standard mammography mode, typically used for screening mammography,tube arm assembly 106 and compression arm assembly 110 are coupled andlocked together by 410 in a relative position such as seen in FIG. 1,such that an x-ray beam from x-ray tube assembly 108 illuminates x-rayreceptor 502 when the patient's breast is compressed by compressiondevice 112. In this mode, the system operates in a manner similar tosaid Selenia™ system to take a mammogram. Vertical travel assembly 404and tube arm rotation mechanism 406 can make vertical adjustments toaccommodate a patient, and can rotate tube arm assembly 106 andcompression arm assembly 110 together as 1 unit about axis 402 fordifferent image orientations such as for CC and for MLO images. Forexample, tube arm assembly 106 and compression arm assembly 110 canrotate between (−195°) and (+150°) about axis 402. As in the Selenia™system, compression device 112 includes a compression paddle 122 thatcan move laterally, in a direction along the chest wall of a patient, toadjust for different imaging orientations. However, as described furtherbelow, the mechanism for supporting and moving compression paddle 122 isdifferent. Typically, anti-scatter grid 504 is over x-ray receptor 502to the standard mammography mode to reduce the effect of x-ray scatter.FIG. 8 illustrates a typical workflow for an exposure in standardmammography mode, and FIG. 10 illustrates an example of the operation ofdetector subsystem 117 in standard mammography. Of course, these areonly examples; other workflow steps or orders of steps can be usedinstead.

In a diagnostic mode, the patient's breast can be spaced from uppersurface 116, for example by an x-ray translucent spacer gantry 1002(FIG. 10), with the system otherwise similar to FIG. 1, for amagnification of up to 1.8, for example. In this mode, as in standardmammography, tube arm assembly 106 and compression arm assembly 110 arelocked to each other and can move up or down and rotate about axis 402for different image orientation. A different spacer 1002 can be used fora different degree of magnification. Also, differently shaped ordimensioned compression paddles 122 can be used for different breastcompression effects. The x-ray tube in x-ray tube assembly 108 can beset to a smaller focal spot size to improve a diagnostic image. In thismode, anti-scatter grid 504 typically is retracted when magnification isused such that grid 504 is completely out of the image. The user canelect not to a spacer 1002 in diagnostic imaging, in which caseanti-scatter grid 504 can be used over the entire image.

In a dynamic imaging mode, a number of breast images are taken while thepatient's breast remains compressed. In one technique, an agent such asiodine is injected into the patient and after a suitable waiting time,such as about one minute for a maximum uptake, two images of the breastare taken in rapid succession, for example one at an x-ray energy justabove the K-edge of iodine and one at an energy just below the K-edge.Alternatively, a succession of breast images can be taken at a singlex-ray energy band or bands just above and below the K-edge, or atanother x-ray energy range, to track the uptake of agent over time.Another technique adds taking a baseline breast image before or soonafter injecting the agent and using it together with later breast imagesto generate subtraction images that provide better visualization ofanatomy that may be of interest. Still another dynamic imaging modetechnique comprises injecting a contrast agent and taking a successionof images over a period such as 5-7 minutes, for example one image everyminute, and processing the image data to generate for each pixel, or atleast for each pixel of interest, a histogram of the change in the pixelvalue, to thereby use the manner in which pixel values change todifferentiate abnormal tissue. For this mode, work-station 102 can storepreset data that commands gantry 100 and work-station 102 to take adesired sequence of images for the dynamic mode technique selected bythe operator, such that the command data sets the appropriate parameterssuch as x-ray energy, dose, timing of images, etc. Alternatively, suchprocessing to assess changes in pixel values can be done for a region ofinterest rather than over individual pixels, to produce information suchas a measure of changes in the average pixel values in the region ofinterest.

In tomosynthesis mode, tube arm assembly 106 and compression armassembly 110 are decoupled by unit 410 such that compression armassembly 110 stays in one position, compressing the patient's breast,while tube arm assembly 106 rotates about axis 402, for example betweenthe position illustrated in FIG. 2 to that illustrated in FIG. 11, or±15° relative to compression arm assembly 110. Tomosynthesis can becarried out for different image orientations, so that compression armassembly 110 can be rotated about axis 402 (alone or together withassembly 106) for a desired image orientation and locked in place, andthen tube arm assembly 106 can be rotated relative to that position ofcompression arm assembly 110 for tomosynthesis imaging over ±15° or someother desired angular range. In one example, 11 images are taken duringan angular sweep of tube arm assembly 106, one every approximately 3°.However, a different number of images can be taken, for example up to 21during a single sweep. For tomosynthesis images, the x-ray tube in x-raytube assembly 108 continuously rotates and the x-ray tube is pulsed foreach image, for example, for x-ray energy pulses each lastingapproximately 100 mSec, although pulses of different duration can beselected. Alternatively, the rotational motion can stop for taking eachimage, or continuous motion without pulsing can be used (and the timingof data measurements relied to define pixel values). As seen in FIGS. 2,3, 5, 11 and 12, in this mode mechanism 506 fully refracts anti-scattergrid 504 away from x-ray receptor 502 so grid 504 is out of the image.Also as seen in these Figs., while the breast remains immobilized incompression arm assembly 110 during the angular sweep of tube armassembly 106, x-ray receptor 502 rocks within receptor housing 114. Inthis rocking motion, controlled by unit 408 (FIG. 4), a line normal tothe image face of x-ray receptor 502 may keep pointing to the focal spotof the x-ray tube in x-ray tube assembly 108. Alternatively, therotation of tube arm assembly 106 and rocking of x-ray receptor 502 canbe through different angles; for example, tube arm assembly 106 canrotate through 150 while x-ray receptor 502 rocks through 5°, i.e. therocking angle can be an amount one-third that of assembly 108.Synchronous rotation of tube arm assembly 106 and rocking of x-rayreceptor 502 can be achieved by controlling separate motors for each or,alternatively, through using a motor to drive tube arm assembly 106 anda mechanical coupling between the rotation of tube arm assembly 106 androcking of x-ray receptor 502. Image data can be obtained and processedinto tomosynthesis images for display and/or storage as described in thematerial incorporated by reference, for example in co-pending patentapplication Ser. No. 10/723,486 or in U.S. Provisional Application No.60/628,516, filed Nov. 15, 2004. FIG. 13 illustrates a typical workflowfor tomosynthesis mode operation, and FIG. 14 illustrates an example ofthe operation of detector subsystem 117 in that mode. Again, these areonly examples, and other steps or orders of stops can be used instead.

In a combination mode, during a single compression of the patient'sbreast the system takes a conventional mammogram and tomosynthesisimages. In this mode, while the breast remains compressed in compressionarm assembly 110, (1) tube arm assembly 106 sweeps and x-ray receptor502 rocks, each through an appropriate angle, and exposures are takenfor tomosynthesis images, and (2) a standard mammogram is taken. Thestandard mammogram can be taken at a 0° relative angle between tube armassembly 106 and a normal to the imaging plane of x-ray receptor 502,and can be taken before or after the tomosynthesis images are taken orbetween the taking of two successive tomosynthesis images. Typically,each tomosynthesis image utilizes substantially lower x-ray dose thanthe standard mammogram. For example, the total x-ray dosage fortomosynthesis imaging in one sweep of tube arm assembly 106 can beapproximately the same as that for a single standard mammogram, or up toapproximately three times the mammogram dosage. The relationship betweenthe two dosages can be user-selected. FIG. 15 illustrates an example ofworkflow for the combination mode, and FIG. 16 illustrates an example ofthe operation of detector subsystem 117 in that mode. Again, these areexamples, and different steps or orders of steps can be used instead.For example, a preferred approach may be to take the standard mammogramfirst, then move arm 106 to one end of its rotational range fortomosynthesis and take the tomosynthesis images. The order in which thetwo types of images are taken may be optimized such that the overallimaging time is minimized, and an order that achieves such minimizationcan be the preferred order. The exposure (tube current mA, tube voltagekVp, and exposure length msec) techniques for the standard mammogram andthe tomosynthesis exposures can be set manually, or by using automaticmethods. If the standard mammogram is taken first, its exposuretechniques can be used to set an optimal technique for the subsequenttomosynthesis images, and vice versa. The exposure technique can bemodified dynamically, if the software senses that the signal reachingthe image receptor is either too low or too high, and subsequentexposures may be adjusted as needed.

In a stereotactic mode, during a single compression of the patient'sbreast at least two images are taken, for example one at (+15°) angleand one at (−15°) angle of tube arm assembly 106 relative to compressionarm assembly 110, although other angles can be used and more images canbe taken. X-ray receptor 502 can remain in place for this procedure, orcan be rocked through a selected angle, for example through an anglesufficient to maintain the same orientation of the imaging surface ofreceptor 502 relative to tube arm assembly 106. A spacer 1002 can beused for magnification. If x-ray receptor 502 remains in place despiterotation of arm 106, or if spacer 1002 is used, anti-scatter grid 504 isfully retracted; if x-ray receptor 502 maintains its orientationrelative to tube arm assembly 106 and not spacer 1002 is used,anti-scatter grid 504 need not be retracted. As is known in the art, thetwo or more images can be used to identify the location of a lesion, sothat needle biopsy can be used, for example with an upright needlebiopsy station 412 (FIG. 4) in a manner similar to that used with thecommercially available Selenia™ system and StereoLoc II™. A compressionpaddle 122 appropriate for needle biopsy typically is used when takingthe stereotactic images. Alternatively, some or all of the images takenin the tomosynthesis mode and/or in the combined mode can be used toidentify the location of a lesion for biopsy, in which case acompression paddle 122 appropriate for the purpose typically is usedwhen taking the images.

In needle localization mode, x-ray images can be taken after a biopsy orother needle is inserted into the compressed breast. For this purpose,imaging such as in the stereotactic mode, the tomosynthesis mode, or thecombined mode can be used.

In the disclosed system, compression paddle 122 is movable laterally, asgenerally described in U.S. Patent Application Publication No.2005/0063509 A1, hereby incorporated by reference herein. In addition,compression paddle 122 can pivot about an axis along the patient's chestwall to conform the breast shape in certain procedures, as discussed insaid U.S. Pat. No. 5,706,327. However, in the system of this patentspecification compression paddle 122 is mounted differently and moves ina different manner.

As illustrated in FIGS. 5 and 17, compression paddle 122 is removablymounted to a support 510 that moves up and down compression arm assembly110 as needed for breast compression. To mount compression paddle 122onto 510, a projection compression paddle 122 a of the paddle engages aprojection 510 a of the support, and a projection 122 b of the paddlelatches onto projection 510 b of the support. Projection 510 a isspring-loaded, such as by a spring schematically illustrated at 510 c toallow for pivoting compression paddle 122 about an axis where it latchesonto 510, as illustrated by arrow A, for better conformance with thecompressed breast in some imaging protocols. Other imaging protocols mayrequire compression paddle 122 not to pivot, in which case projection510 a is locked in place by a locking mechanism in 510 (not shown) tokeep compression paddle 122 in place relative to support 510. Thelocking mechanism can be manually set to a lock position, and manuallyunlocked by the operator. Alternatively, the locking mechanism can becontrolled through an operator input at gantry 100 or work-station 102.A sensing mechanism can be included to sense whether compression paddle122 is locked against pivoting, to provide information that work-station102 can use for setting imaging protocols such as for automated breastcompression and automated exposure methods. Two knobs 510 d, one on eachlateral side of support 510, can be manually rotated to move projection510 b and thus compression paddle 122 laterally such that it compressesa breast that is not centered laterally on upper surface 116, forexample for MLO imaging. Each knob 510 d can operate a mechanism such asan endless screw rotating in a nut secured to projection 510 b.Alternatively, or in addition, projection 510 b and thus compressionpaddle 122 can be driven laterally by a motor, under control of operatorswitches or other interface at gantry 100 or at work-station 102, orautomatically positioned laterally under computer control.

Importantly, compression paddle 122 is driven for lateral movement bycomponents that are a part of support 510. Thus, compression paddle 122can be a simple structure, and can even be disposable, with a new oneused for each patient or for only a few patients. This can simplify andreduce the cost of using the system, because an imaging facility usuallystocks a number of different paddles for different purposes. If thelateral movement mechanism is integral with a compression paddle, thepaddle assembly is considerably larger, heavier and more expensive. Butwith a compression paddle 122 that relies for lateral movement onsupport 510, and is easily mounted by hand and without tools to support510, by sliding compression paddle 122 a into projection 510 a andlatching projection paddle 122 b onto projection 510 b, and is easilyremoved by reversing the process, the expense of keeping a number ofdifferent compression paddles in stock or replacing paddies with newones is greatly reduced, as are the time and convenience when changingfrom one type of compression paddle to another. Compression paddle 122can include a bar code that is automatically read by a bar code readerin support 510, to keep work-station 102 informed of the paddlecurrently mounted to support 510, for use in automating imagingprotocols. For example, the bar code information can be checked toensure through computer processing that the type of paddle that iscurrently mounted on support 510 matches the imaging that will becommanded, and the information from the sensor for whether compressionpaddle 122 is locked in non-tilting mode can be used to automaticallymake adjustments for compression height to ensure accurate automaticx-ray exposure operation. Further, the bar code information identifyingthe paddle can be used to automatically set collimation in x-ray tubeassembly 108 so that the x-ray beam matches the size and shape of thecurrently installed compression paddle 122.

The above specific examples and embodiments are illustrative, and manyvariations can be introduced on these examples and embodiments withoutdeparting from the spirit of the disclosure or from the scope of theappended claims. For example, elements and/or features of differentillustrative embodiments may be combined with each other and/orsubstituted for each other within the scope of this disclosure andappended claims.

This application claims the benefit of U.S. provisional application Ser.No. 60/631,296, filed Nov. 26, 2004 and entitled “INTEGRATED MULTI-MODEMAMMOGRAPHY/TOMOSYNTHESIS X-RAY SYSTEM AND METHOD”, the entire contentsof which are incorporated herein by reference.

The invention claimed is:
 1. A breast tomosynthesis system comprising:an arm assembly; an x-ray source rotatably connected to the armassembly; a compression paddle comprising a front end and a rear end; abiasing mechanism connecting the compression paddle to the arm assembly,wherein the biasing mechanism is configured to cause the front end ofthe compression paddle to tilt about a connection axis disposedproximate a connection of the compression paddle and the arm assembly;and a controller for controlling the x-ray source in a plurality ofimaging modes, wherein the x-ray source is configured to rotate relativeto the compression paddle about an axis for at least one of theplurality of imaging modes.
 2. The breast tomosynthesis system of claim1, further comprising: an x-ray imaging receptor having first and secondlateral sides; and a receptor housing extending from the arm assemblyand concealing the receptor, said receptor housing having a generallyflat upper surface having lateral sides and configured to support apatient's breast between the source and the receptor, with the breastextending away from the patient in a direction generally parallel tosaid lateral sides of the upper surface of the arm assembly, and whereinone of the plurality of imaging modes is a conventional mammographyimaging mode in which the x-ray source and the x-ray image receptor arefixed relative to the receptor housing.
 3. The breast tomosynthesissystem of claim 2, further comprising an anti-scatter grid disposedbetween the compression paddle and the x-ray image receptor for at leastone of the plurality of imaging modes.
 4. The breast tomosynthesissystem of claim 3, wherein the anti-scatter grid is retractable out ofan imaging area for at least one of the plurality of imaging modes.
 5. Abreast tomosynthesis system comprising: a housing; an x-ray source andan x-ray imaging receptor having first and second lateral sides, whereinboth of the x-ray source and the x-ray imaging receptor are supported bythe housing; an arm assembly secured to the housing; a receptor housingextending from the arm assembly and concealing the receptor, saidreceptor housing having a generally flat upper surface having lateralsides and configured to support a patient's breast between the sourceand the receptor, with the breast extending away from the patient in adirection generally parallel to said lateral sides of the upper surfaceof the receptor housing; wherein the x-ray source is connected to thehousing for rotational movement relative to the upper surface of thereceptor housing from a position closer to one of said lateral sides ofthe upper surface of the receptor housing to a position closer to theother lateral side of the upper surface of the receptor housing; acompression paddle comprising a front end and a rear end, wherein thecompression paddle is disposed generally between the source and thereceptor housing; and a biasing mechanism configured to removablyconnect the compression paddle to the arm assembly, wherein the biasingmechanism is configured to cause the front end to tilt against a biasforce relative to the receptor housing as a patient's breast is beingcompressed between the paddle and the upper surface of the receptorhousing such that the front end is further from the upper surface of thereceptor housing than the rear end.
 6. The breast tomosynthesis systemof claim 5, further comprising a support connecting the biasingmechanism and the arm assembly, wherein the biasing mechanism comprises:a support projection; a spring; and a mating element on the compressionpaddle, wherein the spring is configured to bias the support projectioninto latching contact with the mating element.
 7. The breasttomosynthesis system of claim 5, further comprising: a supportprojection; a mating projection disposed on the compression paddle; anda spring for providing a biasing force on at least one of the supportprojection and the mating projection.
 8. The breast tomosynthesis systemof claim 5, wherein the x-ray source and the x-ray imaging receptor areconfigured for movement to accommodate a plurality of imaging modes,wherein the x-ray source is configured to rotate relative to thecompression paddle about an axis for at least one of the plurality ofimaging modes.
 9. The breast tomosynthesis system of claim 8, whereinone of the plurality of imaging modes is a conventional mammographyimaging mode in which the x-ray source and the x-ray image receptor arefixed relative to one another.
 10. The breast tomosynthesis system ofclaim 9, further comprising an anti-scatter grid disposed between thecompression paddle and the x-ray image receptor for at least one of theplurality of imaging modes.
 11. The breast tomosynthesis system of claim10, wherein the anti-scatter grid is retractable out of an imaging areafor at least one of the plurality of imaging modes.
 12. The breasttomosynthesis system of claim 8, wherein at least two or more of theplurality of imaging modes utilize a single breast compression.
 13. Abreast tomosynthesis system comprising: an x-ray source and an x-rayimaging receptor having first and second lateral sides; an arm assembly;a receptor housing extending from the arm assembly and concealing thereceptor, said receptor housing having a generally flat upper surfacehaving lateral sides and configured to support a patient's breastbetween the source and the receptor, with the breast extending away fromthe patient in a direction generally parallel to said lateral sides ofthe upper surface of the receptor housing; a compression paddleconnected to the arm assembly at a connection and comprising a front endand a rear end; a biasing mechanism configured to cause the front end ofthe compression paddle to tilt about a connection axis disposedproximate a connection of the compression paddle and the arm assembly;and a controller for controlling the x-ray source in a plurality ofimaging modes, wherein the x-ray source is configured to rotate relativeto the compression paddle about an axis for at least one of theplurality of imaging modes.
 14. The breast tomosynthesis system of claim13, further comprising a support projection extending from the armassembly, wherein the biasing mechanism comprises: a support projection;a mating element disposed on the compression paddle; and a spring forproviding a biasing force on at least one of the support projection andthe mating element.
 15. The breast tomosynthesis system of claim 14,wherein the spring is connected to at least one of the supportprojection and the mating element.
 16. The breast tomosynthesis systemof claim 13, wherein one of the plurality of imaging modes is aconventional mammography imaging mode in which the x-ray source and thex-ray image receptor are fixed relative to the receptor housing.
 17. Thebreast tomosynthesis system of claim 13, further comprising ananti-scatter grid disposed between the compression paddle and the x-rayimage receptor for at least one of the plurality of imaging modes. 18.The breast tomosynthesis system of claim 17, wherein the anti-scattergrid is retractable out of an imaging area for at least one of theplurality of imaging modes.
 19. The breast tomosynthesis system of claim13, wherein at least two or more of the plurality of imaging modesutilize the same breast compression.